A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
Operation: JOVIAN WHISTLE was an operation executed by the UNSC 717th Xeno-Materials Exploitation Battalion to recover a Forerunner ancilla on the human colony world of Gao in the Cordoba system in the early summer 2553.
Operation: RETRIBUTION was an Office of Naval Intelligence mission headed by operative Veta Lopis and her Ferret team to investigate the murder of Vice Admiral Graselyn Tuwa and the kidnapping of her family members on December 6th, 2553.
The Return to Installation 00 was an Office of Naval Intelligence mission undertaken by the UNSC Rubicon to return to the Ark following the Battle of Installation 00 and investigate the status of the facility in August 2554.
Operation: FAR STORM was a joint UNSC and Swords of Sanghelios mission to reactivate the Portal at Voi and travel back to Installation 00 after discovering the Halo array was counting down to activation in March 2555.
The Invasion of Earth was an attempt by the monitor of Installation 00 to harvest the Earth for resources to repair the Ark when the Portal at Voi was reopened in March of 2555.
Sometime in January 2557, Rion Forge, a post-war salvager, and her ship the Ace of Spades, discover the location of what was left of the Etran Harborage after the destruction of the shield world during the events of the Battle of the Etran Harborage in 2531.
The Battle of Requiem was a conflict between former Covenant forces under the command of Jul 'Mdama, UNSC forces from the UNSC Infinity and Forward unto Dawn, and Promethean forces under command of the Ur-Didact on Forerunner Shield World 0001, also known as Requiem, in July 2557.
The Battle of Installation 03 was a battle between the UNSC and Covenant remnant forces under command of Jul 'Mdama on Gamma Halo during and immediately following the New Phoenix Incident in July 2557.
The Raid on Ivanoff Station was an attack by the Ur-Didact and his ship Mantle's Approach on the Office of Naval Intelligence research facility Ivanoff Station nearby Halo Installation 03 in July 2557.
The New Phoenix Incident was an attack by the Ur-Didact on the Earth city of New Phoenix on July 25th, 2557 using the Composer that he had acquired from Ivanoff Station the day prior.
The Mission to Installation 03 was a UNSC operation to investigate the loss of contact with a science outpost and Spartan-II Black Team on Gamma Halo immediately following the New Phoenix Incident in July 2557.
The Battle of New Phoenix was a military engagement between the UNSC and Covenant remnant forces under command of Jul 'Mdama in the city of New Phoenix on Earth, immediately after the New Phoenix Incident and the Battle of Installation 03 in July 2557.
The Mission to Mount Kilimanjaro was a trek undertaken by 343 Guilty Spark, Rion Forge, and the crew of the Ace of Spades to find the Librarian and, in the case of Spark, gain access to the Domain in September 2557.
The Requiem Campaign was a UNSC mission to return to Requiem, and take control of the shield world away from Jul 'Mdama and his Covenant remnants in February 2558, six months after the Battle of Requiem.
